1. Field of the Invention
This invention relates to servicing telecommunications equipment located in the field.
2. Background Art
Telecommunications systems are typically designed as a collection of distributed central offices interconnected by high speed trunks. Each central office contains switches for routing calls carried over the trunk lines to individual carrier loops running between the central office and subscriber premises.
As the number of customers supported by a central office grows, the capacity to directly connect the central office to each customer can be exceeded. One costly solution is to build more central offices. A less expensive solution is to run a small set of cables from the central office to a field cabinet located close to customer premises. The cables terminate at one or more carrier multiplexers. Each carrier multiplexer supports a plurality of carrier loops. Signals on the carrier loops are multiplexed onto the central office cables. Thus, the central office is capable of supporting a greater number of customers.
A carrier multiplexer which has seen great use in the past is the subscriber loop carrier (SLC) such as, for example, the SLC-96. This device enables up to 96 analog subscriber carrier loops to be served by three central office cables. A typical field cabinet may contain up to five SLC-96 carrier multiplexers. The field cabinet also includes power supply equipment supporting the carrier multiplexers. Typically, up to three carrier multiplexers are supplied by a set of power supply equipment. This equipment includes an AC supply receiving AC current from outside of the cabinet. A rectifier circuit converts line AC to DC, typically xe2x88x9248V, for use by the carrier multiplexers. A ringing voltage circuit converts line AC to ringing AC voltage for driving telephone ringers. A battery back-up system, referred to as a battery tray, provides electrical power in the event of external AC cut-off. Finally, alarm logic monitors conditions within the field cabinet and generates alarms typically received by the central office. Alarms may be based on sensing a variety of conditions including AC supply operation, rectifier operation, ringing voltage operation, battery tray operation, equipment temperature, carrier multiplexer operating status, cabinet door opening, and the like.
The use of carrier multiplexers in remote field cabinets greatly increase the number of subscriber loops which can be supported by a central office. However, once the field cabinet is filled with equipment, and the maximum number of carrier loops supported by this equipment had been dedicated, local capacity is again exhausted. One solution for expansion is to construct another field cabinet to support increasing demand in the area covered by the full field cabinet. However, constructing a new field cabinet is expensive, typically requiring additional easement rights which may not be available as well as the cost of installing another pedestal and AC power feed. Thus, a less expensive alternative is needed.
Improvements in technology permit a greater number of carrier multiplexers to be packed into the same cabinet volume. Similarly, improvements in power supply technology reduce the cabinet volume necessary to support each new carrier multiplexer. However, for cost and functionality reasons, an advantage may be gained by continuing to use existing carrier multiplexers such as the SLC-96.
Thus, a problem arises. Replacing old power supply equipment with newer, smaller power supply equipment creates additional space for more carrier multiplexers. However, output wiring from new power supply equipment is not compatible with older, existing carrier multiplexers. What is needed is to interconnect newer power supply equipment with older carrier multiplexers. This connection scheme should permit a mixture of newer carrier multiplexers and older carrier multiplexers within the same field cabinet. Further, replacing power supply equipment should be done in a manner that disrupts telecommunications services as little as possible.
The present invention permits replacing telecommunications carrier equipment in a field cabinet so as to allow existing carrier multiplexers to be powered by newer, smaller power supply equipment.
A method of replacing telecommunications carrier equipment in a field cabinet is provided. A first set of power supply equipment supporting at least one carrier multiplexer is removed. Each carrier multiplexer has power connections for each power type. The first set of power supply equipment has a supply connection corresponding to each power connection at each power type. All of the plurality of power inputs of each power type for each carrier multiplexer are bridged together. A second set of power supply equipment has a single supply connection corresponding to each power type for each carrier multiplexer. Each of the bridged power inputs for each carrier multiplexer is connected with the corresponding supply connection for each power type.
In an embodiment of the present invention, a central office is notified of possible power related alarms prior to removing the first set of power supply equipment.
In another embodiment of the present invention, at least one new carrier multiplexer is installed. Each new carrier multiplexer has at least one power input corresponding to each of the power types. For each new carrier multiplexer, the at least one power input for each power type is connected with a corresponding power supply connection on the second set of power supply equipment. At least one high-bandwidth cable is connected to the central office side of each new carrier multiplexer. A plurality of carrier loops are connected to the customer premises side of each new carrier multiplexer. The new carrier multiplexer may be a digital carrier system such as, for example, an NEC-ISC-303.
In still another embodiment of the present invention, the second set of power supply equipment comprises a Lucent CPS-4000.
In yet another embodiment of the present invention, at least one carrier multiplexer is an SLC-96.
In a further embodiment of the present invention, the plurality of power types includes xe2x88x9248 VDC and ground return. The plurality of power types may also include positive ringing AC and negative ringing AC.
A remote terminal cabinet is also provided. The cabinet includes a housing located outside of a telecommunications central office. Equipment in the housing is connected to the central office through high-bandwidth cables. Equipment in the housing is connected to customer premises through carrier loops. Carrier multiplexers are disposed within the housing. Each carrier multiplexer multiplexes at least one of the high bandwidth cables to customer premises carrier loops. At least one of the carrier multiplexers has power connections for each power type. A power supply is also disposed within the housing. The power supply has a power supply connection for each power type on each carrier multiplexer. A bridging connection connects power connections for one power type on a carrier multiplexer with a corresponding power supply connection on the power supply.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.